Method for building wind turbine tower

ABSTRACT

A method for erecting a tower includes the steps of providing a first pre-cast section of concrete and positioning it atop a foundation. A radially-inwardly extending ledge is attached to an interior wall of the first pre-cast section and a plurality of jacks is positioned below the ledge in circumferentially spaced apart relation to one another. The ledge and the first pre-cast section are raised to a first height by operating jacks in an ascending mode. A second pre-cast section is positioned beneath the first pre-cast section after the first pre-cast section has been lifted to the first height. The first pre-cast section is lowered onto the second pre-cast section by operating the jacks in a descending mode or the second pre-cast section is lifted by operating the jacks in ascending mode. An assembly building that surrounds a base of the tower protects workers from inclement weather.

FIELD OF THE INVENTION

This invention relates, generally, to methods for erecting tall structures. More particularly, it relates to a method for building a tower that supports a wind turbine.

DESCRIPTION OF THE PRIOR ART

Wind turbines are very heavy and they operate best at high elevations. They are usually mounted atop steel or concrete towers that are not stayed by guy wires. Both types of towers are typically built from the ground up.

One problem with conventional building techniques is that workers must expose themselves to greater and greater heights as tower construction progresses. This problem is exacerbated if the work has to be performed in inclement weather.

Many sites that are ideal for wind turbine farms are in northern climes where winds are strong and temperatures are low for much of the year. When conditions deteriorate to unacceptable levels, work on such towers in the field must be stopped. Construction companies spend the winter months shipping in parts, materials, supplies, and making plans for the construction season. A burst of construction activity than takes place when the weather warms until the work is forced indoors again.

Conventional wind turbine towers are typically constructed from the ground up. The turbine must therefore be lifted to a great height and attached to the top of the tower as the last step in the tower-construction process. Due to the extreme weight of a wind turbine nacelle, the lifting must be performed under very low wind conditions. Accordingly, lengthy delays can be experienced at the very end of the tower-building process.

There is a need, then, for an improved construction method for such towers. The improved method would not expose workers to dangerous heights nor would it expose workers to inclement weather. The improved method would also enable towers to be built throughout the year with no winter, poor weather, or high-winds interruptions.

There is a need as well for a tower construction method that includes mounting the turbine to the top section of the tower while the top section is at ground level so that the turbine-lifting and securing process can be performed at any time of the year and without waiting for very low wind conditions.

However, in view of the prior art taken as a whole at the time the present invention was made, it was not obvious to those of ordinary skill how the identified needs could be fulfilled.

SUMMARY OF THE INVENTION

The long-standing but heretofore unfulfilled need for an improved method for erecting wind turbine towers is now met by a new, useful, and non-obvious invention.

The inventive method for erecting a tower includes the steps of providing a first pre-cast section of concrete having a generally tubular construction and positioning the first pre-cast section at ground level on a previously constructed foundation capable of supporting great weights such as twenty-five hundred tons. The first pre-cast section may be a monolithic section having a hollow, cylindrical shape or a hollow, tapered cylindrical shape where its diameter at its lower end exceeds its diameter at its upper end. The first pre-cast section may also be formed of independently formed arcuate parts that collectively form a pre-cast section when assembled and secured to one another.

The longitudinal axis of the pre-cast section is normal to the weight-bearing foundation. A radially-inwardly extending ledge member, or “haunch,” is detachably secured to an interior wall of the first pre-cast section and at least one jack is positioned below the radially-inwardly extending haunch in circumferentially spaced apart relation to one another if more than one (1) jack is employed so that operating the jacks in an ascending mode raises the ledge member and therefore the first pre-cast section.

A second pre-cast section of concrete is positioned directly below the first pre-cast section after the first pre-cast section is lifted to a first predetermined height. In a first embodiment, the first pre-cast section is then lowered onto the second pre-cast section by operating the jacks in a descending mode.

In a second embodiment, the jacks maintain the first section at its first predetermined height and hydraulic or other suitable means are used to lift the second pre-cast section into engagement with the elevated first pre-cast section. This avoids the surrendering of elevation and the subsequent re-gaining of said elevation required by the first embodiment, i.e., the second embodiments avoids operating the jacks in the descending mode when the jacks are under load.

The hydraulic means of the second embodiment includes a plurality of hydraulic cylinders positioned below a platform that is vertically movable in relation to the weight-bearing foundation. When fully retracted, the platform is disposed in a cavity formed in the foundation and the top surface of the platform is flush with the top surface of the foundation. The distance over which such hydraulic cylinders must operate is substantially equal to a clearance distance between the bottom or trailing end of the first pre-cast concrete section and the top or leading end of the second pre-cast concrete section that is positioned beneath the first section when said first section has been elevated to its first predetermined height. When fully extended, the platform lifts the second section so that the clearance space is closed, i.e., so that the top of the second section abuts the bottom of the first section. The platform remains elevated until the first and second sections have been secured to one another. It then returns to its fully retracted position of repose and its cycle is repeated for each individual pre-cast section until the tower is completed.

In the first embodiment, the jacks are lowered to their initial, lowermost position after the first section has been lowered onto the second section and said sections have been secured to one another. All materials that need to cure are substantially cured before any further lifting is performed.

In the second embodiment, the jacks are lowered to their initial, lowermost position while the hydraulic cylinders continue to support the platform in its elevated position and hence the first and second sections in their respective elevated positions. The haunches are then placed onto the second section and the jacks are lifted to support said haunches and hence said first and second sections. The hydraulic cylinders are then retracted back into their position of repose, thereby returning the platform to its fully retracted position where its top surface is flush with the top surface of the weight-bearing foundation. The cavity that receives the platform has the same depth as the height dimension of the platform so that when the platform is in its fully retracted position of repose, it is flush with the foundation.

In a third embodiment, the movable platform is eliminated. Instead, a plurality of jacks are positioned in cavities formed in the foundation The jacks are aligned with the pre-cast concrete sections and lift them directly as needed to close the clearance space between an elevated pre-cast section and the pre-cast section disposed directly below it on the foundation.

In a fourth embodiment, the pre-cast sections are off-loaded at the assembly building from a railroad car onto a wheeled cart and the wheeled cart or other such vehicle positions the pre-cast section directly below an elevated section. For example, in an embodiment where a pre-cast section has three (3) parts that are assembled to create the section, then three (3) carts would be employed.

In a first variation of the fourth embodiment, each cart is equipped with jacks to lift its load upwardly until the lower pre-cast section abuts the elevated one, i.e., until the clearance space is eliminated.

In a second variation of the fourth embodiment, jacks in the foundation lift the load from the carts.

In all embodiments, the radially-inwardly extending haunches may be detached from the first pre-cast section and attached to the second pre-cast section after the first and second sections are disposed in abutting end-to-end relation to one another and after said first and second sections have been joined together at said abutting ends. However, the haunches may also be provided with clearance spaces through which the jacks may travel so that the haunches need not be detached. The jacks are then operated in their ascending mode to lift the first and second pre-cast sections to a predetermined height sufficient to enable insertion of a third pre-cast section below the second pre-cast section, in the first embodiment, the jacks are again operated in their descending mode to lower the first and second pre-cast sections in surmounting relation to the third section. In the second embodiment, the hydraulic cylinders are again operated to lift the platform so that the top or leading end of the third section enters into abutting relation to the bottom or trailing end of the second section.

The tower is completed by repeating the same steps for as many sections of pre-cast concrete as needed. The jacks are preferably equidistantly spaced apart from one another so that they share a common load. They are operated slowly in both their ascending and descending modes and they are operated so that each jack performs lifting and lowering at a rate in common with the other jacks.

The climbing jacks may or may not be used in a fifth embodiment. A frusto-conical lift plug having the same shape and size as the hollow interior of the top section of the tower is snugly inserted into said hollow interior of said top section of the tower when said top section is at ground level. As in the first two embodiments, the wind turbine is preferably placed into surmounting relation to the first section before said first section is elevated. However, it is within the scope of this invention that the nacelle not be lifted into its operable position until the tower is completed. The lift plug and hence the first section with the turbine there atop are hydraulically lifted to a first elevation as in the first two embodiments to provide clearance for the second section. After the second section is in place directly under said elevated first section, the elevated first section may be lowered as in the first embodiment or the second section may be lifted into mating engagement with the first, elevated section as disclosed in connection with the second, third, or fourth embodiments. The two sections are interconnected in the same way as in the first two embodiments. That procedure is repeated until the tower is completed.

Guy wires are preferably used during construction of the tower. They are preferably mounted on computer-controlled reels so that they remain taught at all times, whether the tower is rising or descending as in the first embodiment or rising only as in the other embodiments.

The novel method also includes the steps of erecting an assembly building that surrounds a base of the tower to protect workers, parts, equipment, and materials from inclement weather and temperature extremes. An opening in a roof of the assembly building is provided to accommodate erection of the tower and closure means for said opening may be provided. The assembly building provides a controlled environment not just for worker comfort but also so that multiple materials may be used even if outdoor conditions would prevent their use. For example, welding is problematic in extreme cold, as is concrete pouring and curing. With a controlled environment within the confines of the assembly building, many routine construction procedures that are interrupted by inclement weather can continue without interruption throughout the year.

The assembly building also has utility in enhancing the stability of the tower in the same way that a boss helps stabilize an upstanding post. The assembly building has further utility in connection with the deployment of guy wires.

Construction details include the step of embedding respective first ends of a plurality of vertically oriented rebars in the second pre-cast section so that respective second ends of said rebars extend from a top or leading horizontal end wall of the second pre-cast section. A plurality of mating sockets is formed in a horizontal bottom or trailing end wall of the first pre-cast section so that the respective second ends of the vertically oriented rebars are received within the respective sockets when the first pre-cast section surmounts the second pre-cast section. The first section of the tower is the only section that does not require rebars protruding from its top horizontal end wall unless such rebars are useful in securing a turbine to said top horizontal end wall. The final, bottom section of the tower is the only tower section that does not require sockets formed in its bottom or trailing horizontal end wall.

The connecting structure just disclosed could also be reversed, i.e., the rebars could extend downwardly from the upper section and the rebar-receiving sockets could be formed in the lower section. The invention is not limited to any particular connection. The abutting ends of contiguous sections could be welded, bolted, or otherwise connected to one another. Post-tensioned connections could also be used.

For towers that are relatively short in height, each pre-cast section can be formed in tubular form, i.e., as a monolithic unit, with each section except the top section having upwardly extending rebars protruding from its horizontal top end wall and each section except the bottom section having sockets formed in its horizontal bottom end wall.

For larger towers, some or all of the pre-cast sections may be too large to transport to the construction site if manufactured in tubular, monolithic form. It may be practical, however, to manufacture two (2) pre-cast sections, each of which forms a semicircle, and to transport such semicircular sections to the construction site. Very tall towers may require three (3) or more pre-cast sections to make one (1) tubular section when the three (3) or more sections are assembled together. Short towers can also be manufactured in easily-transportable sub-sections that are assembled at a construction site into the generally tubular form of a tower section.

When a tubular pre-cast section is to be assembled from two (2) or more arcuate sub-sections, the sub-sections are joined to one another much like the tubular sections are joined to one another when vertically stacked. More particularly, a first vertical edge of each arcuate sub-section is provided with at least one rebar having a first end embedded within the pre-cast arcuate sub-section so that a second end protrudes in a horizontal plane from said vertical edge. A second vertical edge of each arcuate sub-section is provided with at least one horizontally disposed mating socket for accommodating a rebar projecting from a contiguous sub-section. All rebar/socket connections, whether on the top and bottom horizontal end walls or on the vertical side walls of a pre-cast section, are filled with grout, epoxy, or the like after the rebars and sockets are fully coupled to one another and the grout or epoxy is allowed to substantially cure before a pre-cast tubular section is lifted to make room for the next pre-cast section. The parts may also be joined together by welding, various mechanical couplings, and so on. This invention is not limited to any particular fastening or coupling means.

Alternatively, the sub-sections may be bolted or welded to one another along their abutting vertical edges, or by other suitable connections, such as post-tensioned connections, just as the abutting horizontal ends of the respective sections may be joined to one another.

The preferred jacks used in the first two embodiments are climbing jacks of the type that climb steel poles. Each steel pole is positioned radially inwardly of the radially-inwardly extending ledge or haunch member that is attached to each pre-cast section. The steel poles are braced with reinforcing poles or other bracing means that may be positioned radially inwardly of the steel poles in parallel or other supporting relation thereto. The reinforcing poles are braced with horizontally disposed braces that interconnect opposed reinforcing poles. The braces are positioned at a predetermined height so that they do not interfere with movement of workers within the hollow interior of the pre-cast section that is at ground level.

Although this disclosure is primarily based upon an all-concrete tower, it is important to note that not every section need be formed of concrete. For example, the weight of the tower can be reduced by making one or more sections out of a non-cementitous material such as steel. The first section of the tower, i.e., the one surmounted by the nacelle, could be formed of steel, for example. The second section could also be formed of steel, and so on. Any percentage of the tower may be formed of materials other than concrete. It is therefore understood that this invention is not limited in scope to all-concrete towers.

An important object of this invention is to enable construction of tall wind turbine towers, or towers for other purposes, without requiring construction workers to climb to unsafe heights.

Another important object is to disclose a construction procedure whereby a turbine weighing three hundred fifty to five hundred tons or more is elevated to the top of a tower while the top section of the tower is supported by a ground level foundation so that the heavy weight is erected at an elevation where wind is not as large a factor as when lifting a turbine to the top of a conventional tower after the tower has reached its maximum height.

Another important object is to enable construction workers to erect a tall tower while the workers and parts, equipment, materials and the like are protected from inclement weather and temperature extremes by an assembly building.

An object closely related to the preceding object is to provide a construction method that can follow a predetermined schedule without regard to weather conditions so that such towers can be installed on a dependable time schedule.

Another object is to provide a tower made from concrete or other suitable materials so that the tower is very stable and can resist high winds.

Yet another object is to provide a tower made from modular parts so that the modular parts can be made on or off site in a controlled manufacturing environment and transported to a construction site for assembly in a controlled manufacturing environment.

Another important object is to employ guy wires to stabilize the tower as its height increases.

An object closely related to the foregoing object is to provide guy wires that are mounted on computer-controlled reels so that the guy wires remain taut during all phases of the construction process, including upward and downward travel of the pre-cast sections if the first embodiment is used and including upward travel only if the other embodiments are used.

These and other important objects, advantages, and features of the invention will become clear as this description proceeds.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which:

FIG. 1A is a side elevational view of the novel assembly shop and a tower near the beginning of the construction process;

FIG. 1B is a side elevational view of the novel assembly shop and the tower after completion of about a fourth of the construction process;

FIG. 1C is a top plan view of the structures depicted in FIGS. 1A and 1B;

FIG. 1D is a side elevational view of the novel assembly shop and the tower after completion of about half of the construction process;

FIG. 1E is a side elevational view of the novel assembly shop and the tower after completion of about three-fourths of the construction process;

FIG. 1F is a side elevational view of the novel assembly shop and a tower after completion of the construction process;

FIG. 2A is a top plan view of three (3) pre-cast concrete parts having a common height and a common curvature prior to their attachment to one another;

FIG. 2B is a top plan view like that of FIG. 2A, depicting said three (3) pre-cast concrete parts in their assembled configuration;

FIG. 3A is a perspective view of a pre-cast concrete section, depicting a radially-inwardly extending ledge or haunch detachably secured thereto;

FIG. 3B is an exploded perspective view of the pre-cast concrete section depicted in FIG. 3A;

FIG. 4A is a sectional view depicting a climbing jack disposed beneath a ledge or haunch prior to lifting of a first pre-cast concrete section;

FIG. 4B is a sectional view depicting the first pre-cast section when lifted about half way to its maximum elevation;

FIG. 4C is a sectional view depicting the first pre-cast concrete section in its fully elevated position;

FIG. 4D is a sectional view depicting a second pre-cast concrete section that has been placed into position beneath the first pre-cast concrete section and depicting the clearance space between the trailing end of the top section and the leading end of the bottom section;

FIG. 4E is a sectional view depicting the first pre-cast concrete section when it has been lowered into surmounting relation to the second pre-cast concrete section;

FIG. 5A is a sectional view in five (5) animations depicting the use of a cart in a trench to carry the sub-sections from a delivery station to the assembly station;

FIG. 5B is the second view of said five views;

FIG. 5C is the third view of said five views;

FIG. 5D is the fourth view of said five views;

FIG. 5E is the fifth view of said five views;

FIG. 6A is a side elevational sectional view of the second embodiment depicting the first tower section in its first elevated position and depicting the clearance space between the trailing end of the top section and the leading end of the bottom section and depicting the platform of the second embodiment in its fully retracted position;

FIG. 6B is a side elevational sectional view depicting the second tower section positioned in abutting relation to said first tower section and depicting the platform in its fully elevated position;

FIG. 6C is a side elevational sectional view like that of FIG. 5B but depicting the installation of the haunches when the climbing jacks are returned to their respective lowermost positions;

FIG. 6D is a side elevational sectional view depicting the climbing jacks at their respective uppermost positions to provide clearance for the next pre-cast section to be moved into position under the elevated section;

FIG. 7A is the first side elevational view of an animation of four views depicting the lifting of a sub-section into abutting relation to a previously elevated section to close a clearance gap between the two sections;

FIG. 7B is the second view in said animation;

FIG. 7C is the third view in said animation;

FIG. 7D is the fourth view in said animation;

FIG. 8A is the first side elevational view of an animation of three views depicting use of a cart in lifting a sub-section into abutting relation to a previously elevated sub-section to close a clearance gap between the two sections;

FIG. 8B is the second view in said animation;

FIG. 8C is the third view in said animation;

FIG. 9A is the first side elevational view of an animation of three views depicting the use of a cart in lifting a sub-section into abutting relation to a previously elevated section to close a clearance gap between the two sections;

FIG. 9B is the second view in said animation;

FIG. 9C is the third view in said animation;

FIG. 10A is a perspective view of a wheeled vehicle carrying no load and positioned near the position of the wheeled vehicle depicted in FIG. 9A;

FIG. 10B is a perspective view of a wheeled vehicle carrying no load and positioned near the position of the wheeled vehicle depicted in FIGS. 9B and 9C;

FIG. 10C is a perspective view of a wheeled vehicle carrying a load and positioned near the position of the wheeled vehicle depicted in FIG. 9A;

FIG. 11 is a top plan view depicting the braces that support the steel poles of the climbing jacks;

FIG. 12A is the first side elevational, diagrammatic view in a series of seven views that animate the steps of a third embodiment, up to the assembly of the first three sections of the novel tower;

FIG. 12B is the second view in said series of seven views;

FIG. 12C is the third view in said series;

FIG. 12D is the fourth view in said series;

FIG. 12E is the fifth view in said series;

FIG. 12F is the sixth view in said series;

FIG. 12G is the seventh view in said series;

FIG. 13 is a cross-sectional view taken along line 13-13 in FIG. 12G;

FIG. 14 is a side elevational view of a completed third embodiment tower prior to retraction of the lift plug;

FIG. 15 is a diagrammatic view depicting subterranean access into the hollow interior of the tower; and

FIG. 16 is a perspective view of a completed tower with a nacelle wind turbine in surmounting relation to the tower.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1A-F, it will there be seen that an illustrative embodiment of the invention is denoted as a whole by the reference numeral 10.

Structure 10 includes wind turbine 12 that surmounts first section 14 a of tower 14. The first section, and any other section, may be made of pre-cast concrete, concrete prepared at the site, or a non-cementitious material such as steel. Assembly building 16 at the base of the tower protects the workers, parts, materials, supplies and equipment used to erect the tower from the elements and temperature extremes during construction. It can be taken down and moved to a new construction site when the work is completed or it can be left in place to provide shelter. Guy wires 18 a, 18 b are conventional and radiate outwardly in at least three directions as depicted in the plan view of FIG. 1C. This invention includes a novel method for guy wire usage as the tower is erected as best indicated by the arrows in FIGS. 1D and 1E. More particularly, since the guy wires must remain taut as the tower sections are elevated, the unreeling of the guy wires from their respective reels must be coordinated with the lifting motion of the jacks. In the first embodiment, where the tower is lowered a small distance with each new section, the reeling in of the guy wires must be coordinated with the lowering motion. The coordination of reeling guy wires in or out at a rate to match the lifting or lowering rate of the jacks is preferably computer-controlled.

The blades connected to wind turbine 12 are not depicted to simplify the drawing. The blades and turbine 12 are not a part of the invention per se.

Tower 14 is formed of multiple sections which are referred to primarily as pre-cast concrete sections for convenience, with the understanding that the invention is not limited to pre-cast concrete sections as aforesaid. In the depicted example, the sections are denoted 14 a-h. This invention is not limited to any particular number, size or shape of sections. For example, the pre-cast sections could form a generally triangular structure in horizontal cross-section where three (3) straight sides of a triangle are interconnected by arcuate corners or where three (3) arcuate sides of a triangle include straight sections at each end.

Tower 14 is hollow and each section is therefore generally tubular in configuration in a preferred embodiment of the invention. The tower is preferably tapered to have a diameter that gradually reduces with height. Each pre-cast section therefore has a diameter at its top or leading end that is less than its diameter at its lowermost or trailing end. Towers that are not tapered are also within the scope of this invention. However, if a tower has a uniform diameter from top to bottom, the turbine that surmounts the tower must be cantilevered to a greater extent than is required with a tapered tower because the blades must not strike the tower. The increased overhang of the turbine relative to its support as required by an untapered tower increases the stresses on the structure. Moreover, an untapered tower could be much heavier than a tapered tower.

FIGS. 2A and 2B are top plan views depicting how each section 14 is assembled inside building 16. In this particular embodiment, three (3) railroad tracks 11 a, 11 b, and 11 c are positioned in equidistantly, circumferentially spaced relation to one another so that first section 14 a may be assembled from three (3) arcuate sub-sections 1, 2, 3, each of which is small and light enough to be transported over public highways or railways to the construction site. Depending upon the application, the sub-sections could be reduced to only two (2) semicircular parts or the number of sub-sections could be greater than three (3). A pre-cast concrete section having a diameter sufficiently small so as not to require assembly is also within the scope of this invention. For example, the top section of a tower may have a diameter sufficiently small to avoid any need for making said top section in sub-sections, and the same may be true for other highly elevated sections.

As depicted in FIG. 2A, a first vertical end wall of each arcuate part has recess or socket 19 a formed therein and a second vertical end wall has rebar 19 b formed therein. The confronting rebars and recesses thus mate with one another when sub-sections 1, 2, and 3 are displaced radially inwardly from their respective FIG. 2A positions to their respective FIG. 2B positions. Grout or other bonding material is then introduced into each recess and allowed to cure to create a solid joint. In this way, each pre-cast section of tower 14 when fully assembled has a structural integrity substantially similar to what it would be if the section were integrally formed. The tower is never lifted nor lowered until all connections are completely finished and all materials that need to cure have been cured to the required strength. The climate-controlled assembly building facilitates the making of all connections and the curing of all materials because said connections and curing processes are made within said building.

Section 14 a, the section at the top of the tower, is the first section assembled. Turbine 12 is placed atop said section by any suitable means, including a conventional crane, after the grout has cured. This is an important feature of the invention because it eliminates the dangerous and difficult prior art practice of lifting the turbine to the top of the tower as the final step in the tower construction process.

As depicted in FIGS. 3A and 3B, each arcuate pre-cast sub-section includes a pair of radially-inwardly extending ledges or haunches 15. Each haunch 15 may be formed of pre-cast concrete, steel, or other strong material. For reasons that will become clear as this disclosure continues, each haunch may be integrally formed with its pre-cast sub-section or it may be detachably secured to its associated sub-section. When the haunches are to be detachably secured, a bore or socket, denoted 15 a is formed in each pre-cast sub-section on their respective radially inwardly facing surfaces as depicted in FIG. 3B and a corresponding number of plugs in the form of protruding rebars, collectively denoted 15 b, are formed in the respective radially outwardly facing surfaces of each haunch as also depicted in FIG. 3B. The haunches are much lighter in weight than the sub-sections to which they are attached so the plugs are inserted into the sockets by any feasible means. No grout is added in applications where the plugs are disengaged from their associated sockets after each section lifting operation is performed. The climbing jacks are returned to their respective lowermost positions after each sub-section is lifted to a height that allows a subsequent sub-section to be positioned beneath it. Where the haunches are integrally formed with their respective pre-cast concrete sections, a passageway is formed in them so that the climbing jacks may pass through such passageway, thereby eliminating the need to remove the haunches after each lift.

Referring now to FIGS. 4A-4E, it will be understood in connection with those Figs. that a conventional crane, such as a traveling crane, is preferably used to lift the nacelle to the top of the first pre-cast concrete section at the beginning of the construction process. However, placing the nacelle atop a completed tower near the end of the construction process is also within the scope of this invention.

As best understood in connection with FIGS. 4A-E and FIGS. 5A-E, each climbing jack 20 requires a vertical steel pole 22 to climb. Each jack includes a first pair of upper opposed plates and a second pair of lower opposed plates; said first and second pairs of opposed plates are vertically spaced apart from one another. When the upper plates converge toward one another to engage the steel pole, the lower plates diverge away from one another so as not to engage said steel pole. When the upper plates tightly engage the steel pole, the vertical distance between the upper opposed plates and the lower opposed plate is reduced, i.e., the lower opposed plates travel upwardly under hydraulic power to a point on the steel pole directly under the upper opposed plates. The lower plates then tightly engage the steel pole. After the steel pole is fully engaged by the lower plates, the upper plates release their grip on the steel pole and the upper plates are raised under hydraulic power until they are a predetermined distance above the lower plates. Upon reaching said predetermined distance, the upper plates again engage the steel pole. After said upper plates have fully engaged the steel pole, the lower plates release their grip on said steel pole and the above-recited steps are repeated. The tower is lifted when the upper plates are raised; they engage the bottom surface of their respective haunches.

The climbing jacks and their associated steel poles are positioned radially inwardly of the pre-cast concrete sub-sections. When each climbing jack is in its fully lowered position, as depicted in FIG. 4A, uppermost end 20 a of each climbing jack is at an elevation slightly lower than an underside of each haunch or ledge 15. Climbing jacks 20 are hydraulically powered and operate in synchronization with each other and with the guy cables so that each pre-cast concrete section is held level as it is lifted. When section 14 a (turbine 12 being omitted to simplify the drawing) attains a height greater than the combined height of section 14 b of tower 14 and the needed clearance space, the sub-sections of section 14 b, of which there are three in this particular example, are brought together and secured to one another in the manner recited above. The climbing jacks then climb down their respective steel poles at a common rate of descent, gently lowering the turbine atop said assembled section 14 a. The climbing jacks continue climbing down their respective steel poles until they reach their respective initial position of repose as depicted in FIG. 4A as aforesaid.

More particularly, FIG. 4B depicts section 14 a after it has been lifted a short distance and FIG. 4C depicts section 14 a after it has been lifted to a height sufficient to receive section 14 b beneath it. FIG. 4D depicts section 14 b after it has been moved into position beneath said section 14 a and FIG. 4E depicts section 14 a after it has been lowered into surmounting relation to section 14 b.

Each pre-cast sub-section 1, 2, 3 has a plurality of rebars, collectively denoted 13 a, extending from its uppermost horizontal end wall and a corresponding number of rebar-receiving sockets, collectively denoted 13 b, formed in its lowermost horizontal end wall.

After section 14 a has been lifted and section 14 b moved into place beneath it, and after said section 14 a has been lowered into surmounting relation to said section 14 b as aforesaid, radially-extending haunches 15 are then detachably secured to their respective arcuate sub-sections 1, 2, 3. The radially innermost edge of each haunch when connected to its associated arcuate part, is radially outwardly of each steel pole 22. The lifting surface of each climbing jack is positioned below its associated haunch. Thus, as climbing jacks 20 ascend their associated steel poles 22 at a common rate of ascent, their associated haunches 15 and hence sub-sections 1, 2, and 3 are thereby lifted.

The climbing jacks are operated until the bottom or trailing of section 14 a is positioned above the floor of building 16 by a distance equal to the height of section 14 b, including the height of rebars 13 a projecting upwardly therefrom, and a further preselected clearance distance to ensure that said bottom of section 14 a will not interfere with the interlocking of sub-sections 1, 2, and 3 of section 14 b when said section 14 b is assembled in the same manner as section 14 a. When section 14 b is fully assembled and the grout or other bonding material around the rebars has substantially cured, the climbing jacks are lowered so that rebars 13 a projecting upwardly from section 14 b enter into their associated sockets 13 b formed in the bottom end wall of section 14 a as section 14 a is lowered into overlying relation to section 14 b.

Haunches 15 are then removed from section 14 a and said haunches are lowered so that they can be detachably secured to section 14 b.

This process is repeated for the remaining sections. Only one (1) set of ledges or haunches is needed.

However, if haunches 15 are formed integrally with their respective pre-cast sections, the climbing jacks travel through a clearance space or passageway formed in the haunches to enable the climbing jacks to descend without being blocked by the haunches.

FIGS. 4A-E do not depict a means for bringing second section 14 b from its FIG. 4C position to its FIG. 4D position. Theoretically, if friction forces are not too high, the sub-sections resting atop the support surface could simply be pushed or pulled by any means until they converge with one another and line up underneath elevated first sub-section 14 a.

FIGS. 5A-5E depict an embodiment where the support surface of the tower is a thick concrete pad or platform 32. A trench or ditch 32 a is formed in concrete platform 32 and a cart, preferably supported by railroad tracks, is adapted to travel in said ditch. Each cart 17 a includes a platform 30 that can be hydraulically lifted and lowered. A pre-cast sub-section of the tower is taken from a railroad car and deposited atop platform 30 when platform 30 is slightly elevated as depicted in FIG. 5A. The depth of the ditch or trench and the height of the cart are predetermined so that when the cart travels away from the railroad car to the position of FIG. 5B, the bottom edge of the pre-cast section will clear the top surface of platform 32 by a short distance. This moves the sub-section to its FIG. 5B position without sliding said sub-section atop platform 32. When cart 17 a attains its FIG. 5B position, platform 30 is hydraulically lowered until the sub-section is supported by platform 32. This removes the load from platform 30 of cart 17 a and enables the cart to return on its tracks to the station where it receives its next load. Cart 17 a therefore never carries more than the weight of one sub-section and platform 32 carries the load of the tower as it is lowered to make each connection between the sub-sections.

FIGS. 6A-D depict a second embodiment of the invention. This embodiment eliminates the need to lower the tower to join the horizontal trailing wall of an upper section to the horizontal leading wall of its contiguous lower section.

As depicted in FIG. 6A, hydraulic cylinders 30 are mounted in thick concrete foundation 32 that overlies ground 34. Concrete platform 36 is mounted within a cavity formed in foundation 32 so that the top surface of said platform is flush with the top surface of foundation 32 when platform 36 is in its fully retracted position as depicted in FIG. 6A. In FIG. 6A, first section 14 a has been elevated by the climbing jacks and second section 14 b has been positioned directly below said first section. Accordingly, there is a clearance space between the bottom of section 14 a and the top of section 14 b.

Activation of a hydraulic motor or motors causes cylinders 30 to rise upwardly to lift platform 36 and second section 14 b to their respective positions depicted in FIG. 6B. This closes the clearance space and sections 14 a and 14 b are then connected to one another by the various connections means disclosed above, or any other suitable connection means. With the full weight of the tower supported by hydraulically-lifted platform 36, a control signal sent to the climbing jacks enables them to climb downwardly from their respective elevated FIG. 6A positions to their respective lowered FIG. 6B positions.

Haunches 15 are then installed onto section 14 b as depicted in FIG. 6C and another control signal again activates the climbing jacks to lift pre-cast section 14 b a distance to enable the next pre-cast section or sub-sections to be positioned under it as depicted in FIG. 6D. With the full weight of the tower bearing upon the climbing jacks, platform retracts 36 to its initial position of repose, flush with foundation 32, to enable said next pre-cast section or sub-sections to be moved into place as depicted in said FIG. 6D.

Due to the weight of the tower, it is desirable to reinforce each steel pole 22. As depicted in FIGS. 5A-E and FIG. 6A-D, one way of doing that is to position a second reinforcing steel pole 23 radially inwardly of each climbing jack steel pole 22 and to interconnect said poles to one another at vertically spaced intervals as at 25. Plural braces, denoted 27 a-d, are then positioned in horizontally-disposed, bracing relation to opposed steel poles 23 as depicted. Braces 27 a are positioned about seven feet (7′) above the floor of building 16 so as not to interfere with movement of workers in the building. At least one additional set of braces may also be provided above the first set of braces.

FIGS. 7A-D depict a third embodiment where movable platform 36 is eliminated. Hydraulic jacks 30 are positioned within cavities 30 a formed within concrete foundation 32 so that their respective lifting surfaces are flush with the top surface of foundation 32 when the jacks are fully retracted as depicted in FIGS. 7A and 7D. As depicted in FIG. 7B, a pre-cast section is lifted by a distance sufficient to close the clearance gap between the bottom edge of an elevated pre-cast concrete section and a top edge of a pre-cast section supported by said foundation. After the upper edge of the lower section has been bonded or otherwise coupled to the lower edge of the upper section, jacks 30 are then retracted and the process continues as before. FIG. 7C depicts the attachment of a haunch while a jack means 30 is extended but the jacks may also be employed in haunch-less embodiments.

FIGS. 8A-C depict a fourth embodiment. Each pre-cast section or sub-section is transferred from a railroad car or other delivery vehicle to a wheeled cart 17 a or other suitable vehicle and the cart or carts travel a short distance from the delivery vehicle to the tower erection site as depicted in FIG. 8A. Carts 17 a are preferably self-propelled but may be pushed or pulled. Each cart 17 a travels to a position where the concrete section or sub-section it carries is aligned directly below the elevated section as depicted in FIG. 8B. Hydraulic jacks 30 are built-in to each cart and when activated lift the section or sub-section upwardly into abutting relation to the elevated section as depicted in FIG. 8C.

FIGS. 9A-C depict a variation of the fourth embodiment. Instead of jacks 30 being built-into the carts, said jacks 30 are mounted in concrete foundation 32, just as in the third embodiment. They extend through openings formed in cart 17 a and lift the load as needed, holding the section or sub-section in place until the lifted section is secured to the elevated section.

FIG. 10A depicts a cart 17 a in a position similar to the position of FIG. 9A, but when carrying no load. FIG. 10B depicts a cart 17 a in a position similar to the position of FIGS. 9B and 9C, but when carrying no load. FIG. 10C depicts a cart 17 a in a position similar to the position of FIG. 9A, and when carrying a load.

The carts could be much wider than the carts that are depicted so as to provide a more stable support for the concrete sections or subsections. Moreover, additional jacks could be provided in flanking relation to the depicted jacks, whether or not the carts are provided in a wider form.

FIG. 11 is a top plan view depicting six (6) climbing jacks 20 and therefore six (6) steel poles 22, six (6) reinforcing steel poles 23 and three (3) sets of diametrically extending braces 27. The number and spacing of said jacks and poles is changed for differing applications, it being understood that the number of jacks and associated steel poles may increase as the height and weigh of the pre-cast concrete tower increases.

The lifting of section 14 a to accommodate section 14 b therebeneath lifts the bottom end wall of said section 14 a above the roof of building 16, or nearly so, depending upon the selected height of building 16 and the overall height of section 14 b. Due to the relatively short extent of the combined heights of sections 14 a and 14 b, guy wires may not be required as depicted to help secure said section 14 a against swaying. However, guy wires will be required as the tower increases in height.

A fifth embodiment is depicted in FIGS. 12A-G, 13 and 14. Wind turbine 12 and assembly building 16 are deleted from these Figs. to simplify them.

As depicted in FIG. 12A, frusto-conical lift plug 40 having the same shape and size as the hollow interior of top section 14 a of the tower is centered on platform 36 and the sub-sections of section 14 a are installed around it and secured to one another. Accordingly, lift plug 40 is snugly received within the hollow interior of top section 14 a when said top section is at ground level. The turbine is not depicted to simplify the drawing but said turbine is lifted and deposited atop section 14 a after said first section has been assembled but before said first section is elevated.

Lift plug 40 and hence first section 14 a with the turbine thereatop are hydraulically lifted to a first elevation as in the first two embodiments to provide clearance for second section 14 b as best understood in connection with FIG. 11B. Hydraulic shaft 42 is centered within the interior of lift plug 40 and is driven upwardly by a hydraulic motor, not depicted. Platform 36 remains in its fully retracted position as depicted in FIG. 11B or said platform is eliminated as in the third and fourth embodiments.

Hydraulic shaft 42 could be provided in relatively short sections so that it would not need to extend downwardly into the earth as drawn. A new section of shaft could be positioned directly under an elevated shaft by a revolving mechanism such as provided in revolver-type pistols, for example. The revolving mechanism would rotate atop concrete foundation 32 and its chambers would be re-loaded as needed. The ends of the shaft sections would be coupled together by any suitable means to collectively form shaft 42. Such short sections could also be positioned in alignment with main shaft 42 and connected thereto in many ordinary ways. They could be carried into position by carts, they could be slid atop foundation 32 while in an upright configuration, they could be rolled to the center of the structure and then stood up to enter into alignment with the main shaft, and so on.

In FIG. 12C, the sub-sections of second section 14 b have been displaced radially inwardly into their assembled configuration directly below elevated section 14 a. The elevation of first tower section 14 a is such that a clearance space is provided between sections 14 a and 14 b, just as in the first two embodiments.

After second section 14 b is in place directly under said elevated first section 14 a, foundation 36 is raised by hydraulic cylinders 30 as in the second embodiment and as depicted in FIG. 12D to lift second section 14 b into mating engagement with first section 14 a and the two sections are interconnected in the same way as in the first two embodiments. Said elevation of second section 14 b eliminates the clearance space depicted in FIG. 12C.

Hydraulic cylinders 30 then retract and platform 36 is lowered to its position of repose as depicted in FIG. 12E.

As depicted in FIG. 11F, hydraulic cylinder or shaft 42 is then extended further so that second section 14 b attains an elevation sufficient to move the sub-sections of tower section 14 c into position directly below section 14 b.

Hydraulic cylinders 30 then lift section 14 c into mating engagement with section 14 b by elevating platform 36 as depicted in FIG. 12G.

The procedure depicted in FIGS. 12A-G is repeated until the tower is completed. Lift plug 40 is retracted from the hollow interior of first section 14 a and lowered into overlying relation to platform 36 to conclude tower construction.

FIG. 13 is a transverse sectional view of section 14 b as indicated in FIG. 12G.

FIG. 15 diagrammatically depicts subterranean tunnel 44 that provides ingress and egress into and out of the hollow interior of tower 14. Where a center shaft such as hydraulic cylinder 42 is used, the entrance to the tunnel would not be centered in the building as depicted. A centered entrance is suitable for the embodiments that employ climbing jacks.

A completed tower having eight (8) sections, each made of three (3) sub-sections, surmounted by nacelle 12, is depicted in FIG. 16.

Building 16 protects all participants in the tower-construction project from inclement weather, and the novel method eliminates the need for any worker to be exposed to heights. This enables tower construction to continue unabated in inclement weather. The use of guy wires also enables tower construction to continue even in relatively high wind conditions. Building 16 also provides a temperature-controlled environment that enables the making of connections that include grout, epoxy, or other temperature-sensitive materials. These features enable a tower to be raised much faster than a tower built by conventional from bottom to top methods. The use of pre-cast concrete sections and the novel from top to bottom method speeds the process even more, thereby significantly reducing labor and other costs associated with building pre-cast towers.

The use of multiple climbing jacks that are reinforced as disclosed herein enables the building of pre-cast concrete towers that may exceed three hundred feet in height and which may have weights in excess of two thousand (2000) tons. The lift plug embodiment can do the same but it is disclosed primarily to indicate that the invention is not limited to the use of climbing jacks.

It will thus be seen that the objects set forth above, and those made apparent from the foregoing description, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween. 

1. A method for erecting a tower formed of multiple sections, comprising the steps of: providing a foundation for supporting said tower; providing a first section and positioning said first section atop said foundation; securing at least one radially-inwardly extending ledge member to an interior wall of said first section; positioning a jack means below said at least one radially-inwardly extending ledge member; lifting said at least one radially-inwardly extending ledge member and hence said first section to a first predetermined height by operating said jack means in an ascending mode; and positioning a second section beneath said first section after said first section has been lifted to said first predetermined height, said first predetermined height being substantially equal to a height of said second section and a predetermined clearance space.
 2. The method of claim 1, further comprising the steps of: lowering said first section onto said second section by operating said first plurality of jack means in a descending mode.
 3. The method of claim 2, further comprising the steps of: securing a trailing end of said first section to a leading end of said second section.
 4. The method of claim 3, further comprising the steps of: securing at least one radially-inwardly extending ledge member to an interior wall of said second section; positioning said first plurality of jack means below each of said at least one radially-inwardly extending ledge member so that the jack means of said first plurality of jack means are circumferentially spaced apart from one another; lifting said at least one radially-inwardly extending ledge member and hence said second section to said first predetermined height by operating said first plurality of jack means in an ascending mode; and positioning a third section beneath said second section after said second section has been lifted to said first predetermined height.
 5. The method of claim 1, further comprising the steps of: forming a trench having a predetermined extent in said foundation; providing a cart adapted to shuttle along said extent between an outer end and an inner end of said trench; said cart adapted to carry a sub-section of a section from said outer end of said trench toward said inner end so that said sub-section does not contact a top surface of said foundation when said sub-section is in transport; said cart adapted to lower said subsection so that said sub-section is supported by said foundation and not said cart when said sub-section is delivered by said cart to a position from which said sub-section is to be elevated.
 6. The method of claim 5, further comprising the steps of: said cart having a platform that is raised when said cart carries said sub-section to said position from which said sub-section is to be elevated; said platform of said cart being lowered below a plane defined by said top surface of said foundation after said cart delivers said sub-section to said position from which said sub-section is to be elevated.
 7. The method of claim 1, further comprising the steps of: forming a cavity in said foundation; positioning a vertically-movable platform in said cavity, said platform having a fully retracted position where a top surface of said platform is flush with a top surface of said foundation; lifting said second section into abutting relation with said first section by elevating said platform; connecting said first and second sections to one another while said platform is elevated; and lowering said platform after said step of connecting said first and second sections to one another is accomplished.
 8. The method of claim 1, further comprising the steps of: forming a plurality of cavities in said foundation; providing a second plurality of jack means; positioning a jack means of said second plurality of jack means into at least some of the cavities of said plurality of cavities; lifting said second section into abutting relation to said first section by operating said second plurality of jack means in an ascending mode.
 9. The method of claim 8, further comprising the steps of: securing a trailing end of said first section to a leading end of said second section.
 10. The method of claim 9, further comprising the steps of: securing a radially-inwardly extending ledge member to an interior wall of said second section; positioning said first plurality of jack means below said radially-inwardly extending ledge member so that the jack means of said first plurality of jack means are circumferentially spaced apart from one another; lifting said radially-inwardly extending ledge member and hence said second section to said first predetermined height by operating said second plurality of jack means in an ascending mode; and positioning a third section beneath said second section after said second section has been lifted to said first predetermined height.
 11. The method of claim 1, further comprising the steps of: providing said first plurality of jack means in the form of climbing jacks having steel poles; arranging said circumferentially spaced apart climbing jacks in equidistantly spaced relation to one another; positioning a first brace member between at least two opposed steel poles.
 12. The method of claim 11, further comprising the steps of: positioning said first brace member at a predetermined height within the hollow interior of said first section so that said brace member does not interfere with movements of workers within said hollow interior of said second section when said first section is elevated to a height sufficient to provide clearance for said second section.
 13. A method for erecting a tower, comprising the steps of: providing a foundation for supporting said tower; providing a first section and positioning said first section atop said foundation; lifting said first section to a first predetermined height; providing a vehicle adapted to carry a second section from a remote location onto said foundation and aligning said second section with said first section; mounting a plurality of jack means in said vehicle; lifting said second section into abutting relation to said first section by operating said jack means in an ascending mode; securing said first and second sections to one another; and lowering said jack means after said first and second sections are secured to one another.
 14. A method for erecting a tower, comprising the steps of: providing a foundation for supporting said tower; providing a plurality of cavities in said foundation; positioning a jack means in at least one of said cavities so that a lifting surface of said jack means is substantially flush with a top surface of said foundation when said jack means is fully retracted; providing a first section and positioning said first section atop said foundation; lifting said first section to a first predetermined height; providing a vehicle adapted to carry a second section from a remote location onto said foundation and aligning said second section with said first section; forming at least one opening in said vehicle such that said at least one opening is aligned with said at least one jack means when said second section is aligned with said first section; lifting said second section into abutting relation to said first section by operating said jack means in an ascending mode; securing said first and second sections to one another; and fully retracting said jack means after said first and second sections have been secured to one another.
 15. A method for erecting a tower of multiple sections, comprising the steps of: providing a foundation for supporting said tower; positioning a lift plug atop said foundation; assembling a first section of said tower around said lift plug; lifting said lift plug and hence said first section to a first elevation, said first elevation being substantially equal to a vertical distance equal to a height of a section of said tower and a clearance distance; positioning a second section directly below said first section; lifting said second section into abutting relation to said first section; and securing a leading end of said second section to a trailing end of said first section.
 16. A method for erecting a tower that includes multiple sections, comprising the steps of: providing a foundation for supporting said tower; positioning a lift plug atop said foundation; assembling a first section of said tower around said lift plug; lifting said lift plug and hence said first section to a first predetermined height, said first predetermined height being substantially equal to a vertical distance equal to a height of a section of said tower and a clearance distance; positioning a second section directly below said first section; bringing said first and second sections into abutting relation to one another; and securing a leading end of said second section to a trailing end of said first section.
 17. The method of claim 16, further comprising the steps of: bringing said first and second sections into abutting relation to one another by lowering said first section onto said second section.
 18. The method of claim 17, further comprising the steps of: bringing said first and second sections into abutting relation to one another by lifting said second section into abutting relation to said first section.
 19. The method of claim 1, further comprising the steps of: erecting an assembly building that surrounds a base of said tower to protect workers from inclement weather; providing an opening in a roof of said assembly building to accommodate erection of said tower.
 20. The method of claim 1, further comprising the steps of: embedding respective first ends of a plurality of vertically oriented rebars in said second section so that respective second ends of said rebars extend from a top horizontal end wall of said second section; and forming a plurality of mating sockets in a horizontal bottom end wall of said first section so that said respective second ends of said vertically oriented rebars are received within said respective sockets when said first section surmounts said second section.
 21. The method of claim 1, further comprising the steps of: embedding respective first ends of a plurality of vertically oriented rebars in said first section so that respective second ends of said rebars extend from a bottom horizontal end wall of said first section; and forming a plurality of mating sockets in a horizontal top end wall of said second section so that said respective second ends of said vertically oriented rebars are received within said respective sockets when said first section surmounts said second section.
 22. The method of claim 1, further comprising the steps of: positioning a turbine in surmounting relation to said first section prior to the step of lifting said first section to said first predetermined height.
 23. The method of claim 1, further comprising the step of: forming at least one of the sections of said tower of concrete.
 24. The method of claim 1, further comprising the step of: forming at least one of the sections of said tower of pre-cast concrete.
 25. The method of claim 1, further comprising the step of: forming at least one of the sections of said tower of a non-cementitious material.
 26. The method of claim 1, further comprising the step of: forming at least one of the sections of said tower of steel. 